The disclosure relates generally to turbomachines, and more particularly, to an auto thermal valve (ATV) for dual mode passive cooling flow modulation.
Turbines are widely used in a variety of aviation, industrial, and power generation applications to perform work. Each turbine generally includes alternating stages of peripherally mounted stator vanes and rotating blades. The stator vanes may be attached to a stationary component such as a casing that surrounds the turbine, and the rotating blades may be attached to a rotor located along an axial centerline of the turbine. A compressed working fluid, such as steam, combustion gases, or air, flows along a gas path through the turbine to produce work. The stator vanes accelerate and direct the compressed working fluid onto a subsequent stage of rotating blades to impart motion to the rotating blades, thus turning the rotor and performing work. If any compressed working fluid moves radially outside of the desired flow path, the efficiency of the turbine may be reduced. As a result, the casing surrounding the turbine often includes a radially inner shell of shrouds, often formed in segments. The shrouds surround and define the outer perimeter of the hot gas path and may be located around both stator vanes and rotating blades.
Turbine shrouds and other turbine components (e.g., blades, nozzles, etc.) are typically cooled in some fashion to remove heat transferred by the hot gas path. A gas such as compressed air from an upstream compressor may be supplied through at least one cooling circuit including one or more cooling passages to cool the turbine shroud and other turbine components.
Tuning pins may be used to control the flow of cooling gas passing through the cooling passages. The flow of cooling gas may be controlled using the tuning pins according to the operational conditions of the turbine (e.g., a higher flow of cooling gas may be required on a hot day, while a lower flow of cooling gas may be required on a cool day). Such flow control may be provided by manuallyadjusting the tuning pins to regulate the flow of cooling gas as needed.